1. Field of the Invention
This invention in general relates to sonar reflectors, and particularly to a low cost passive acoustic target and navigational aid.
2. Description of the Prior Art
Various navigational aids have been devised for assisting submersible vessels in ocean bottom search and/or survey applications. Very often a large number of corner reflectors or transponders are laid out in a grid network so that with proper interrogating signals, the submersible vessel may get an indication of its location with respect to the grid. These devices may be laid out in a more extensive array to serve as navigational markers.
In the case of corner reflectors, however, the interrogating signal is returned to the interrogating vessel and is not individually indentifiable. The transponder, which is an automated receiver/transmitter is able to transmit a unique identifying signal when triggered by an interrogating signal, however the cost of providing transponders over an extensive navigational network becomes prohibitive and in addition, the transponders are active devices requiring power supplies.